Choke

ABSTRACT

A choke for high voltage mains. The choke includes two identical partial windings having turns wound in opposite directions to one another. The magnetic circuit includes a ferromagnetic upper yoke and a ferromagnetic lower yoke. The upper ends of the partial windings are electrically connected to the upper yoke to which is applied the full potential to be applied to the choke and the lower ends of the partial windings are electrically connected to the lower yoke. The magnetic circuit includes two magnetic core members extending between the upper yoke and the lower yoke. The partial windings are each disposed respectively about individual ones of the magnetic core members. Two insulating columns each having an upper opening and a lower opening surround respectively individual ones of the partial windings. Two shielding members are positioned respectively about individual ones of the yoke members. The shielding members and the yoke members are effective to close off the upper and lower openings of the insulating columns from space outside of the choke.

United States Patent Miiller 51 Sept. 12, 1972 1' CHOKE FOREIGN PATENTSOR APPLICATIONS [72] Inventor: Walter Miiller, Schwabach, Ger- 732,2812/1943 Germany ..336/184 many [73] Assignee: Transformatoren UnionAktienreesellschafi, Biased-Be? a statt, Germ any [22] Filed: Dec. 10,1971 [21] Appl. No.: 206,828

[30] Foreign Application Priority Data Dec. 10, 1970 Germany ..P 20 60682.0 Dec. 10, 1970 Germany...l-1GM 70 45 527.5

[52] US. Cl. ..336/60, 336/65, 336/84, 336/184, 336/212, 336/219 [51]Int. Cl ..H0lf 27/10, HOlf 15/04 [58] Field of Search ..336/60, 55, 65,90, 92, 180, 336/184, 84, 212, 219, 234,12

7/1965 Wetherill ..336/212 X Primary Examiner-Thomas J. Kozma Attornqeorge H. Spencer, et al.

[5 7] ABSTRACT A choke for high voltage mains. The choke includes twoidentical partial windings having turns wound in opposite directions toone another. The magnetic circuit includes a ferromagnetic upper yokeand a ferromagnetic lower yoke. The upper ends of the partial windingsare electrically connected to the upper yoke to which is applied thefull potential to be applied to the choke and the lower ends of thepartial windings are electrically connected to the lower yoke. Themagnetic circuit includes two magnetic core members extending betweenthe upper yoke and the lower yoke. The partial windings are eachdisposed respectively about individual ones of the magnetic coremembers. Two insulating columns each having an upper opening and a loweropening surround respectively individual ones of the partial windings.Two shielding members are positioned respectively about individual onesof g the yoke members. The shielding members and the yoke members areeffective to close off the upper and lower openings of the insulatingcolumns from space outside of the choke.

20 Claims, 5 Drawing Figures PRTENTEDSEP I 2 I972 SHEET 1 OF 5PATENTEBSEI' 1 2 m SNEU 3 BF 5 FIG. 3

PHENTEDSEP 12 I972 SHEU 5 0F 5 FIG. 5

CHOKE BACKGROUND OF THE INVENTION This invention relates to a chokehaving two identical, parallel connected, partial windings. The presentinvention more particularly, relates to a choke for very high voltagepower mains and has two identical, parallel connected partial windings,the turns of the windings being wound in opposite directions withrespect to one another, the partial windings being connected together inparallel by ferromagnetic yokes which also connect the cores of therespective partial windings and the upper yoke carrying the fullpotential applied to the choke.

Such chokes are designed principally for the voltage between a conductorand ground and are used to compensate for the reactive power of theline. At the same time the stability of the transmission is increasedand the amplitude of surge voltages caused by switching operations inthe line are reduced.

The previously known configurations of such chokes which are usuallycombinations of single-phase units into three-phase alternating currentassemblies differ substantially in the design of their magneticcircuits. Arrangements are known which have air gaps distributed in thewound portions. Chokes without cores with and without return legs havealso been constructed. The chokes designed for high power and very highvoltages have in common, independent of their core design, that themagnetic circuit and the windings are accommodated in a housingcontaining oil. The housing, sometimes referred to as tank, is made ofsheet metal, usually steel. The core member or members and the housing,in such known chokes, are at ground potential and the end of thewindings at the high tension side is brought out of the housing via abushing. The windings must be fully electrically insulated from the coremember or members and the housing at the high voltage side. Inmultiphase systems, only at the end of the windings connected with aground star point a graded insulation can be used.

U.S. Pat. No. 3,195,082 discloses an arrangement of windings and amagnetic circuit for a choke with an oilfilled housing. The arrangementincludes two identical core portions and two also identicalparallel-connected partial windings, the windings being wound in theopposite direction from one another. The upper yoke in this knownarrangement carries the full potential applied to the choke. This knownarrangement, however, is not satisfactory because it requiresconsiderable expenditures for insulation as do the other knownarrangements. The structural size of chokes constructed as proposed inthe above-mentioned United States Patent is determined, to a largeextent, by prescribed, required distances which depend on the operatingvoltage. Moreover, the required bushing substantially increases the costand requires one-half of the available structural height of the choke.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a choke for high voltage mains which, compared to the knownarrangements, requires much less insulation without any reduction in theoperational safety.

It is another object of the present invention to provide a choke forhigh voltage mains which can be produced easily and has smallerdimensions than comparable known chokes.

The above-stated objects, as well as others which will become clear fromthe text which follows, are accomplished according to the presentinvention by providing a magnetic circuit which includes a ferromagneticupper yoke and a ferro-magnetic lower yoke. Two identical partialwindings having turns wound in opposite directions to one another havetheir upper ends electrically connected to the upper yoke and theirlower ends electrically connected to the lower yoke. The magneticcircuit includes two magnetic core members extending between the upperyoke and the lower yoke. The partial windings are each disposedrespectively about individual ones of the magnetic core members. Twoinsulating columns, each having an upper opening and a lower opening,surround respectively individual ones of the partial windings. Twoshielding members are provided, each being positioned respectively overindividual ones of the yoke members. The shielding members and the yokemembers are effective to close off theupper and lower openings of theinsulating columns from space outside the choke.

According to a more detailed advantageous embodiment of the presentinvention it is provided that the upper ends of the partial windings,the upper yoke and the associated shielding member are electricallyconnected together. The lower ends of the partial windings, the loweryoke and its associated shielding member may be similarly electricallyconnected together.

Both magnetic core members, in an advantageous further embodiment, areconstructed of partial sections with intermediate, ferromagnetic flangesto which winding ends of partial winding sections are connected andwhich close the electrical as well as the magnetic circuit. Theintermediate flanges are surrounded by a shielding member in the form ofa ring.

The insulating columns may be porcelain supports and mechanicalcompression of the windings is preferably effected by porcelainstraining chains.

Each magnetic core member desirably contains a core formed of aplurality of electrically insulated metal lamination packets and thepartial windings are formed of disc coils. The thus produced highlongitudinal capacitance of the partial windings effects a veryfavorable potential control along the insulating surface as well as analmost uniform voltage surge distribution to the individual gaps of thecore.

The choke according to the present invention may be provided with meansfor liquid cooling the choke.

When the choke of the present invention is used as a reactor, ripplefilter choke, in an arrangement for the transmission of direct currents,the lower yoke is placed on at least one and preferably two additionalinsulating columns to insulate electrically the partial windings fromground. The additional insulating columns are hollow and servesimultaneously to conduct the coolant. A possibly required compensationvessel for the coolant is provided by a recess in the shielding memberassociated with the upper yoke.

The choke having the construction according to the present invention isvery advantageous because it permits the elimination of the entire maininsulation of the winding, including the high voltage bushing as well asthe metallic housing and a substantial amount of the coolant. Moreover,the reduction of the ground capacitances of the partial windings to thestray capacitance of the air, on the one hand, and the slimconfiguration originating from the spark gaps, on the other hand,greatly reduces the voltage surge stresses on the partial windings sothat its internal insulation can also be reduced. Due to the very simpleconstruction it is possible to divide the partial windings and theirassociated core members into partial sections so that even chokes with avery high total output can be transported in relatively small andlightweight partial sections. The partial sections can then be assembledat their intended location. With suitable selection of the structurallengths for the partial sections it is possible to construct module typechokes for a basic voltage and multiples thereof from the same type ofelement.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinalcross-sectional view of a choke according to an embodiment of thepresent invention, the section being taken along line 11 of FIG. 2.

FIG. 2 is a side view of the choke illustrated in FIG. 1.

FIG. 3 is a longitudinal cross-sectional view of a second fullyinsulated embodiment of the present invention which is particularlyuseful as a ripple filter in high direct voltage mains.

FIGS. 4 and 5 are respectively cross-sectional and side views of afurther, also fully insulated embodiment of the present invention, thesection shown in FIG. 4 being taken along line 4-4 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, achoke for high voltage mains, according to a first exemplary embodimentof the present invention, includes a first magnetic core member 1 and asecond magnetic core member 2. A first partial winding 3 is arrangedaround the core member 1 and a second partial winding 4 is arrangedaround the core member 2. The partial windings 3 and 4 are wound inopposite directions with respect to one another.

The partial windings 3 and 4 are preferably constructed of interleaveddouble coils.

The core member 1 consists of a plurality of metal packets 5 formed oflaminated sheets. The metal packets 5 are electrically insulated onefrom the next by interposed insulating members 6, the insulating members6 being shown disproportionally large for purpose of clarity. The coremember 2 similarly consists of a plurality of metal packets 7 formed oflaminated sheets and electrically insulated one from the next byinterposed insulating members 8, the insulating members 8 also beingshown disproportionally large for purpose of clarity.

The dimensions of the partial winding 3 and the core member 1 are soselected that they may be accommodated within an insulating column 9which is in the form of a porcelain support. The dimensions of thepartial winding 4 and the core member 2 are similarly so Selected thatthey may be accommodated within an insulating column 10 which also is inthe form of a porcelain support. Thus, the insulating supports 9 and 10simultaneously serve as insulation and as a housing of the choke.

As illustrated in FIG. 1, the magnetic core member 1 includes an upperpartial section 11 and a lower partial section 12. The lower frontalface of the upper partial section 11 is developed with an outwardlyextending ferromagnetic flange 13. The upper frontal face of the lowerpartial section 12 is also developed with an outwardly extendingferromagnetic flange 14.

The partial winding 3 includes an upper partial winding section 15 and alower partial winding section 16 which have respectively substantiallyidentical axial lengths as the upper partial section 11 and the lowerpartial section 12 of the core member 1 measured to the lowermost anduppermost lateral surfaces of the flanges l3 and 14, respectively. Theupper partial winding section 15 has its lower end electricallyconnected to the flange l3 and the lower partial winding section 16 hasits upper end connected to the flange 14.

The insulating column 9 includes an upper support section 17 and a lowersupport section 18 which are positioned on opposite sides of the flangesl3 and 14 which extend radially outwardly from the insulating column 9.The flanges 13 and 14 are surrounded by a shielding ring 19.

The flanges 13 and 14 directly contact one another and thus provide theelectrical connection between the upper partial winding section 15 andthe lower partial winding section 16 of the partial winding 3 as well asthe magnetic circuit connection between the upper partial section 11 andthe lower partial section 12 of the core member 1.

The magnetic core member 2 includes an upper partial section 20 and alower partial section 21 The lower frontal face of the upper partialsection 20 and the upper frontal face of the lower partial section 21are developed respectively with radially, outwardly extending flanges 22and 23 which directly contact one another.

The partial winding 4 includes an upper partial winding section 24having its lower end electrically connected to the flange 22 and a lowerpartial winding section 25 having its upper end electrically connectedto the flange 23. The upper and lower partial winding sections 24 and 25have substantially identical axial lengths as the upper partial section20 and the lower partial section 21 of the core member 4 measured to thelowermost and the uppermost lateral surfaces of the flanges 22 and 23,respectively.

On opposite sides of the abutting flanges 22 and 23 are positioned anupper support section 26 and a lower support section 27 whichconstitutes partial sections of the insulating column 10.

The flanges Y22 and 23 extend radially outwardly from the insulatingcolumn 10 and are surrounded by a shielding ring 28. It will beappreciated that the shielding ring 28 and the shielding ring 19 can becombined so as to be of unitary construction.

The flanges 22 and 23 provide the electrical connection between theupper partial winding section 24 and the lower partial winding section25 of the partial winding 4. The flanges 22 and 23 additionally providethe magnetic circuit connection between the upper partial section 20 andthe lower partial section 21 of the core member 4.

- tion.

The core members 1 and 2 rest on a lower yoke 29 which conducts themagnetic flux between the lower ends of the core members 1 and 2. Thelower yoke 29 is, when used as a choke in an alternating voltagetransmission system, at ground potential and thus need not beelectrically insulated. The magnetic flux between the upper ends of thecore members 1 and 2 is conducted by an upper yoke 30 which iselectrically conductively connected with the high voltage terminal 31 ofthe choke.

The lower yoke 29 and the upper yoke 30 are preferably constructed oflaminated sheets in a conventional manner. The yokes 29 and 30 areprovided respectively with shielding members 32 and 33 which arepositioned about them. The insulating columns 9 and 10 are positionedbetween the shielding members 32 and 33.

The upper yoke 30 and the lower yoke 29 are made of electricallyconductive material and thus may serve respectively to provideelectrical connections between the upper ends of the partial windings 3and 4 and between the lower ends of the partial windings 3 and 4; itwill be appreciated that the shielding members 32 and 33 are also madeof conductive material and may, therefore, provide electricalconnections to the partial windings 3 and 4 via the yokes 29 and 30,respectively.

In a preferred embodiment, the upper ends of the partial windings 3 and4, the upper yoke 30 and the shielding member 33 are all electrically,conductively connected. In this case, the high voltage terminal 31 issimply connected directly to the shielding member 33. The lower ends ofthe partial windings 3 and 4, the lower yoke 29 and its associatedshielding member 32 are also electrically conductively connectedtogether.

The upper yoke 30 and the lower yoke 29 serve to seal from outside spacethe upper and lower ends of the core members 1 and 2. Between the coresand the winding and between the winding and the porcelain supportrespectively axially extended channels 34, 35 for the coolant areprovided. The lower shielding member 32 is provided with two apertures37 and 38 which are aligned with the channels 34 and 35.

The apertures 37 and 38, the channels 34 and 35 define a channel forconducting a coolant, such as oil, through the choke structure via inputand output valves (not shown in FIG. 1). It will be understood, however,that the channel for conducting coolant could also include a passagewaythrough the lower yoke 29 and that the coolant system could beself-contained within the choke structure.

A recess 39 is provided within the shielding member 33 to serve as acompensation vessel for the coolant.

In addition to the coolant channel arrangement as shown in FIG. 1,provisions may be made for circulating oil through the partial windings3 and 4 in a known conventional manner. Such a conventional arrangementcould also be used as an alternative to the coolant channel arrangementshown in FIG. 1.

The upper yoke 30 and the lower yoke 29 serve to clamp the adjacentpartial sections of the core members l and 2 together via force suppliedby a plurality of tensioned insulating chains 41 (FIG. 2) which arepreferably of porcelain and extend between the shielding members 33 and32 and are connected thereto by conventional means. The shieldingmembers 33 and 32 also, by reason of the force supplied by theinsulating chains 41, are operative to clamp the adjacent partialwinding sections of the partial windings 3 and 4.

Since the lower yoke 29 may be grounded, the choke embodimentillustrated in FIG. 1 can best be used for single-phase operation or forstar-connected alternating current mains.

When the choke is to be used in high direct voltage transmissionsystems, the lower yoke 29 must be fully insulated as shown in theembodiment of FIG. 3. As shown in FIG. 3, two additional hollow,insulating columns 40 and 42 in the form of porcelain supports areprovided below the lower yoke 29 and its associated shielding member 32.

The hollow insulating columns 40 and 42 are provided respectively withlongitudinal bores 43 and 44 which are disposed in axial alignment withthe apertures 38 and 37, respectively, in the lower shielding member 32.Thus, insulating columns 40 and 42 not only support and insulate thelower yoke 29, but also serve to guide coolant, such as oil, to theaperture 37 and from the aperture 38 in the lower shielding member 32 incooperation with an inlet valve, diagrammatically shown in the numeral45, and an outlet valve diagrammatically shown at the numeral 46.

The remaining parts of the choke illustrated in FIG. 3 correspond tothose of the choke illustrated in FIGS. 1 and 2.

Referring to FIGS. 4 and 5, a choke for high voltage, according to afurther embodiment of the present invention includes a first magneticcore member 36 and a second magnetic core member 47. A first partialwinding 48 and a second partial winding 49 are respectively arrangedaround the core members 36 and 47. The partial windings 48 and 49 arepreferably constructed of interleaved double coils.

The core members 36 and 47 consist of a plurality of metal packetsformed by laminated sheets with electrical insulating members interposedbetween the metal packets similarly to the arrangement of the coremembers shown in FIG. 1.

A hollow insulating column 50, in the form of a porcelain support, isprovided, the partial winding 48 and the core member 36 beingaccommodated within the insulating column 50. A second insulating column51, also in the form of a porcelain support, is arranged to accommodatethe partial winding 49 and the core member 47 The core members 36 and 47rest on a lower yoke 52 which conducts flux between the lower end of thecore member 36 and the lower end of a core member (not illustrated)which is accommodated within a third insulating column 53 shown in FIG.5. The lower yoke 52 also conducts flux between the lower end of thecore member 47 and the lower end of a core member (not illustrated)which is accommodated within an additional insulating column not visiblein FIGS. 4 and 5. The ad ditional insulating column is positioned, withrespect to the insulating column 51 as the insulating column 53 ispositioned with respect to the insulating column 50, the additionalinsulating column being hidden behind the insulating column 51 of FIG. 4and behind the insulating column 53 ofFIG. 5.

In a preferred operating arrangement the two flux paths through thelower yoke 52 are in opposite directions, the lower yoke operating ineffect as a saddle area.

The upper ends of the core members 36 and 47 are positioned respectivelyagainst an upper yoke 54 and an upper yoke 55. The upper yoke 54provides a flux path between the upper end of the core member 36 and thecore member (not illustrated) which is accommodated within theinsulating column 53 (FIG. The upper yoke 55 provides a flux pathbetween the upper end of the core member 47 and the upper end of thecore member (not illustrated) which is accommodated within theadditional insulating column which cannot be seen in FIGS. 4 and 5, itbeing hidden behind insulating column 53 shown in FIG. 5.

The lower yoke 52 and the upper yokes 54 and 55 are preferablyconstructed of laminated sheets. The upper yokes 54 and 55 are providedrespectively with metallic shielding members 56 and 57, and the loweryoke 52 is provided with a metallic shielding member 58.

The upper end of the partial winding 49, the yoke 55 and the shieldingmember 57, as well as the upper end of the partial winding which iswithin the third insulating column 53 (FIG. 5) preferably areelectrically, conductively connected together. The upper end of thepartial winding 48, the yoke 54, the shielding member 56 and the upperend of the partial winding which is accommodatedwithin the additionalinsulating column not visible in FIGS. 4 and 5 are also preferablyelectrically, conductively connected together. Thus direct high voltageconductive connections can be made to the partial windings 48 and 49 viathe shielding members 56 and 57, respectively.

The lower ends of the partial windings 48 and 49, as well as lower endsof the other partial windings not visible in FIGS. 4 and 5, the loweryoke member 52 and the shielding member 58 are preferably electrically,conductively connected together. In this case, conductive connections tothe lower ends of all the partial windings can be made via the shieldingmember 58.

The upper yokes 54 and 55 seal the upper ends of all core members fromoutside space, and the lower yoke 52 seals the lower ends of all coremembers from outside space.

Each of the four core members is provided with channels only coremembers 46 and 47 and their associated channels 59 and 60 being visiblein FIG. 4. Passageways 61 and 62 are provided respectively around theupper yoke members 54 and 55, the passageways 61 and 62 providing fluidcommunication for each of the channels 59 and 60 with their associatedchannels in the other core members which are not visible in FIGS. 4 and5. A fluid passageway, generally designated by the numeral 63, isprovided around the lower yoke 52 for providing fluid communication withthe axial channels 59 and 60. A second passageway,

which is not visible in FIGS. 4 and 5, is provided around the lower yokemember 52 for providing fluid communication with the axial channelsaround the two core members which cannot be seen in FIGS. 4 and 5.

Two additional, hollow, insulating columns 65 and 64 in the form ofporcelain supports are provided below the lower yoke 52 and theshielding member 58. Each of the insulating columns 64 and 65 includes alongitudinally extending bore, only one bore 66 being visible in FIG. 4.The bore 66 is in fluid communication with the passageway 63. Thesimilar bore within the insulating column 64 is in fluid communicationwith the second passageway within the lower yoke members 52.

The two insulating columns 64 and 65 not only support and insulate thelower yoke 52, but also serve to guide coolant, such as oil, toward andaway from the four core members, only core members 36 and 47 beingvisible in FIG. 4. While neither of the upper yokes 54 and 55, asillustrated, is provided with a recess to serve as a compensation vesselfor the coolant, it is to be understood that such recesses may beprovided, the recesses being constructed similarly to the recess 39shown in FIG. 1.

Although each of the core members 46 and 47, as shown in FIG. 4, do nothave flanges, it is to be appreciated that the core members may haveflanges, thereby allowing the choke to be constructed in a modularfashion as shown in FIG. 1, the partial windings and insulating columnsalso being appropriately modified.

It is to be appreciated that for some applications, the choke shown inFIGS. 4 and 5 may be constructed without the additional insulatingcolumns 64 and 65.

Although the choke shown in FIGS. 4 and 5 provide for circulatingcoolant, such as oil, through a coolant channel extending around thecore members and yokes, it is to be appreciated that provisionsadditionally could be made for circulating the coolant through thepartial windings in a known conventional manner or such conventionalarrangement could be used as an alternative to the cooling arrangementshown in FIG. 4.

It will be understood that the above description of the presentinvention is susceptible to various modifications, changes andadaptations, and the same are intended to be comprehended within themeaning and range of equivalents of the appended claims.

I claim 1. A choke for high voltage mains comprising in combination: twosubstantially identical partial windings disposed about respectivemagnetic core members, said partial windings having turns wound inopposite directions to one another and each having an upper end and alower end; a ferromagnetic upper yoke and a ferromagnetic lower yokeconnecting said core members to provide a closed magnetic circuit, saidupper yoke being electrically connected to said upper ends of saidpartial windings and said lower yoke being electrically connected tosaid lower ends of said partial windings; means for connecting the fullpotential to be carried by said choke to said upper yoke; housing meansin the form of two insulating columns each having an upper opening and alower opening, and each surrounding a respective individual one of saidpartial windings; and two shielding members each positioned about arespective individual one of said yoke members, said shielding membersand said yoke members closing off said upper openings and said loweropenings of said insulating columns from the space outside of the choke.

2. A choke as defined in claim 1 further comprising means operativelyarranged within said housing for liquid cooling the choke.

3. A choke as defined in claim 1 wherein said upper ends of said partialwindings, said upper yoke and its associated one of said shieldingmembers are electrically, conductively connected together.

4. A choke as defined in claim 1 wherein said lower ends of said partialwindings, said lower yoke and its associated one of said shieldingmembers are electrically, conductively connected together.

5. A choke as defined in claim 1 wherein said partial windings are eachrespectively composed of partial winding sections, each partial windingsection having an end defining an intermediate point of one of saidpartial windings; said magnetic core members are each constructed ofpartial core sections and each includes an outwardly extendingintermediate flange, a respective one of each of said ends definingintermediate points of said partial windings being connected to arespective one of said flanges and said flanges of adjacent partial coresections being in contact for closing the electrical circuit of thechoke as well as the mag netic circuit of the choke; and furthercomprising a shielding means positioned over at least a portion of saidflanges.

6. A choke as defined in claim 3 wherein said partial windings are eachrespectively composed of partial winding sections, each partial windingsection having an end defining an intermediate point of one of saidpartial windings; said magnetic core members are each constructed ofpartial core sections and each includes an outwardly extendingintermediate flange, a respective one of each of said ends definingintermediate points of said partial windings being connected to arespective one of said flanges and said flanges of adjacent partial coresections being in contact for closing the electrical circuit of thechoke as well as the magnetic circuit of the choke; and furthercomprising a shielding means positioned over at least a portion of saidflanges.

7. A choke as defined in claim 1 wherein said insulating columns eachcomprise a porcelain support means.

8. A choke as defined in claim 3 wherein said insulating columns eachcomprise a porcelain support means.

9. A choke as defined in claim 6 wherein said insulating columns eachcomprise a porcelain support means.

10. A choke as defined in claim 9 further comprising insulating chainmembers connected between said shielding means for clamping said partialwindings.

11. A choke as defined in claim 1 wherein each of said magnetic coremembers comprises a plurality of electrically insulated laminationpackets.

12. A choke as defined in claim 11 wherein each of said partial windingscomprises a plurality of disc coils.

13. A choke as defined in claim 1 further comprising at least oneadditional insulating column disposed beneath said lower yoke forinsulating said lower yoke from reference potential whereby the chokemay be used as a reactor in a transmission circuit for direct cur- 'i d.A choke as defined in claim 4 further comprising at least one additionalinsulating column disposed beneath said lower yoke for insulating saidlower yoke from reference potential whereby the choke may be used as areactor in a transmission circuit for direct current.

15. A choke as defined in claim 2 wherein said means for liquid coolingthe choke comprises channels around said upper yoke, said lower yoke andsaid magnetic core members for the circulation of a liquid coolant.

16. A choke as defined in claim 13 wherein said upper yoke, said loweryoke, said magnetic core members and said at least one additionalinsulating column are provided with channels for circulation of a liquidcoolant.

17. A choke as defined in claim 2 wherein the shielding elementassociated with said upper yoke contains a recess comprising acompensation vessel for liquid coolant.

18. A choke as defined in claim 1 further comprising a third and afourth substantially identical partial winding disposed respectivelyabout additional core members, said third and said fourth partialwindings having turns wound in opposite directions to one another andeach having an upper end and a lower end; a second ferromagnetic upperyoke and said ferromagnetic lower yoke connecting said additional coremembers in parallel to provide a closed magnetic circuit, said secondupper yoke being electrically connected to said upper ends of said thirdand said fourth partial windings and said lower yoke being electricallyconnected to said lower ends of said third and said fourth partialwindings; additional housing means in the form of a third and a fourthinsulating column each having an upper opening and a lower opening andeach surrounding a respective individual one of said third and saidfourth partial windings; a third shielding member positioned about saidsecond upper yoke, said third shielding member and said upper yokeclosing off the upper openings of said third and said fourth insulatingcolumns from space outside of the choke and said lower yoke and itsassociated shielding member closing off the lower openings of said thirdand said fourth insulating columns from space outside the choke.

19. A choke as defined in claim 18 further comprising at least oneadditional insulating column disposed beneath said lower yoke forinsulating said lower yoke from reference potential whereby the chokemay be used as a reactor in a transmission circuit for direct current.

20. A choke as defined in claim 19 wherein the lower ends of saidpartial windings, said lower yoke and its associated one of saidshielding members are electrically, conductively connected together.

1. A choke for high voltage mains comprising in combination: twosubstantially identical partial windings disposed about respectivemagnetic core members, said partial windings having turns wound inopposite directions to one another and each having an upper end and alower end; a ferromagnetic upper yoke and a ferromagnetic lower yokeconnecting said core members to provide a closed magnetic circuit, saidupper yoke being electrically connected to said upper ends of saidpartial windings and said lower yoke being electrically connected tosaid lower ends of said partial windings; means for connecting the fullpotential to be carried by said choke to said upper yoke; housing meansin the form of two insulating columns each having an upper opening and alower opening, and each surrounding a respective individual one of saidpartial windings; and two shielding members each positioned about arespective individual one of said yoke members, said shielding membersand said yoke members closing off said upper openings and said loweropenings of said insulating columns from the space outside of the choke.2. A choke as defined in claim 1 further comprising means operativelyarRanged within said housing for liquid cooling the choke.
 3. A choke asdefined in claim 1 wherein said upper ends of said partial windings,said upper yoke and its associated one of said shielding members areelectrically, conductively connected together.
 4. A choke as defined inclaim 1 wherein said lower ends of said partial windings, said loweryoke and its associated one of said shielding members are electrically,conductively connected together.
 5. A choke as defined in claim 1wherein said partial windings are each respectively composed of partialwinding sections, each partial winding section having an end defining anintermediate point of one of said partial windings; said magnetic coremembers are each constructed of partial core sections and each includesan outwardly extending intermediate flange, a respective one of each ofsaid ends defining intermediate points of said partial windings beingconnected to a respective one of said flanges and said flanges ofadjacent partial core sections being in contact for closing theelectrical circuit of the choke as well as the magnetic circuit of thechoke; and further comprising a shielding means positioned over at leasta portion of said flanges.
 6. A choke as defined in claim 3 wherein saidpartial windings are each respectively composed of partial windingsections, each partial winding section having an end defining anintermediate point of one of said partial windings; said magnetic coremembers are each constructed of partial core sections and each includesan outwardly extending intermediate flange, a respective one of each ofsaid ends defining intermediate points of said partial windings beingconnected to a respective one of said flanges and said flanges ofadjacent partial core sections being in contact for closing theelectrical circuit of the choke as well as the magnetic circuit of thechoke; and further comprising a shielding means positioned over at leasta portion of said flanges.
 7. A choke as defined in claim 1 wherein saidinsulating columns each comprise a porcelain support means.
 8. A chokeas defined in claim 3 wherein said insulating columns each comprise aporcelain support means.
 9. A choke as defined in claim 6 wherein saidinsulating columns each comprise a porcelain support means.
 10. A chokeas defined in claim 9 further comprising insulating chain membersconnected between said shielding means for clamping said partialwindings.
 11. A choke as defined in claim 1 wherein each of saidmagnetic core members comprises a plurality of electrically insulatedlamination packets.
 12. A choke as defined in claim 11 wherein each ofsaid partial windings comprises a plurality of disc coils.
 13. A chokeas defined in claim 1 further comprising at least one additionalinsulating column disposed beneath said lower yoke for insulating saidlower yoke from reference potential whereby the choke may be used as areactor in a transmission circuit for direct current.
 14. A choke asdefined in claim 4 further comprising at least one additional insulatingcolumn disposed beneath said lower yoke for insulating said lower yokefrom reference potential whereby the choke may be used as a reactor in atransmission circuit for direct current.
 15. A choke as defined in claim2 wherein said means for liquid cooling the choke comprises channelsaround said upper yoke, said lower yoke and said magnetic core membersfor the circulation of a liquid coolant.
 16. A choke as defined in claim13 wherein said upper yoke, said lower yoke, said magnetic core membersand said at least one additional insulating column are provided withchannels for circulation of a liquid coolant.
 17. A choke as defined inclaim 2 wherein the shielding element associated with said upper yokecontains a recess comprising a compensation vessel for liquid coolant.18. A choke as defined in claim 1 further comprising a third and afourth substantially identical partial winding disposed respectivelyabouT additional core members, said third and said fourth partialwindings having turns wound in opposite directions to one another andeach having an upper end and a lower end; a second ferromagnetic upperyoke and said ferromagnetic lower yoke connecting said additional coremembers in parallel to provide a closed magnetic circuit, said secondupper yoke being electrically connected to said upper ends of said thirdand said fourth partial windings and said lower yoke being electricallyconnected to said lower ends of said third and said fourth partialwindings; additional housing means in the form of a third and a fourthinsulating column each having an upper opening and a lower opening andeach surrounding a respective individual one of said third and saidfourth partial windings; a third shielding member positioned about saidsecond upper yoke, said third shielding member and said upper yokeclosing off the upper openings of said third and said fourth insulatingcolumns from space outside of the choke and said lower yoke and itsassociated shielding member closing off the lower openings of said thirdand said fourth insulating columns from space outside the choke.
 19. Achoke as defined in claim 18 further comprising at least one additionalinsulating column disposed beneath said lower yoke for insulating saidlower yoke from reference potential whereby the choke may be used as areactor in a transmission circuit for direct current.
 20. A choke asdefined in claim 19 wherein the lower ends of said partial windings,said lower yoke and its associated one of said shielding members areelectrically, conductively connected together.